Those industries which are engaged in activities such as galvanizing, hot-tinning, terne coating, can seam sealing and so on, require the use of flux compositions to aid in the effective cleaning and wetting of the surface to be treated and to obviate the formation of deleterious oxides on the surface of the glavanizing and the like baths which are to be used.
In order to be effective, such fluxes whether top flux or preflux compositions, must have a high degree of chemical activity. This activity is provided by ammonium chloride which is generally present in commercial fluxes at concentrations of 10% by weight or more. Unfortunately, when such quantities of ammonium chloride are used, a high degree of fuming occurs from the flux composition and anti-pollution standards are sometimes violated.
Compromise formulations have been proposed in which the ammonium chloride level is maintained at about 3% by weight to give acceptable fume control and yet allow a measure of oxide-dissolving chemical activity. In fact, however, it has been found that fluxes containing 3% of ammonium chloride are no more effective than those which contain 1% of ammonium chloride while the fluxes containing 3% show a detectable increase in fume evolution.
Other alternatives have been proposed to deal with the problem of adequate chemical activity and low fuming. For example, galvanizing fluxes in which a fluoride salt is employed have been disclosed in U.S. Pat. No. 3,244,551, issued to Sidney M. Heins on April 5, 1966. Low-fuming fluxes have been proposed in which various frothing agents are employed, such as, for example, in U.S. Pat. No. 2,940,870, issued to Allen T. Baldwin on June 14, 1960 and U.S. Pat. No. 2,473,580, issued to Lowell D. Eubank et al. on June 21, 1949. Notwithstanding these suggestions of the prior art, fluxes which are low fuming by virtue of a low concentration of ammonium chloride have been less than highly effective, particularly as measured by commercial standards.